There has been considerable recent interest in halogen substituted hydrocarbons, including a desire to provide effective processes for reducing chlorine and/or bromine content thereof. Hydrogenolysis is a known method for doing this. For example, U.K. Patent 1,578,933 discloses a process for the hydrogenolysis of certain starting materials to tetrafluoroethane using:a hydrogenation catalyst (e.g., palladium supported on alumina or carbon). However, as indicated in U.K. Patent 1,578,933 the tetrafluoroethane product produced is dependent to a large extent on the choice of starting materials. When the organic starting material is CF.sub.3 CCl.sub.2 F (CFC-114a), CF.sub.3 CH.sub.2 F (HFC-134a) is obtained almost to the exclusion of CHF.sub.2 CHF.sub.2 (HFC-134); and when the organic starting material is CClF.sub.2 CClF.sub.2 (CFC-114) the reaction product usually comprises a mixture of the two tetrafluoroethane isomers. Hydrogenolysis can also result in the selective reaction of one isomer in the presence of another. For example, U.S. Pat. No. 4,319,060 discloses a process for the selective hydrogenolysis over a palladium catalyst of CFC-114a in the presence of CFC-114; and describes reacting a feed containing CFC-114 (96-97%) and CFC-114a (3-4%) over Pd/C to produce a mixture containing 95.7 wt. % CFC-114, 2.5 wt. % HFC-134a, 1.0 wt. % HFC-134, and 0.8% of the over-hydrogenated product, CF.sub.3 CH.sub.3. C. Gervasutti et al., J. Fluorine Chem., 19, 1-20 (1981/82) also discloses the hydrogenolysis of dichlorotetrafluoroethane isomers to tetrafluoroethane isomers, and reports that not only is the symmetric isomer, CFC-114, less reactive than the asymmetric isomer, CFC-114a, but also that some of the CFC-114 isomerizes to CFC-114a under reaction conditions. Thus, in the hydrogenolysis of mixtures of fluorochlorocarbons over a hydrogenation catalyst, selective reaction and isomerization can result in a hydrogenation product mix which is different with respect to the distribution of fluorine substituents on carbon atoms from the mix of reactants. Hydrogenolysis of certain fluorochlorocarbons using tube reactors made of various materials has been disclosed. For example, U.S. Pat. No. 2,615,926 discloses use of platinum tubes, U.S. Pat. No. 2,704,775 discloses use of nickel and stainless steel tubes and U.S. Pat. No. 3,042,727 discloses use of a Vycor.RTM. tube.
It is desired to provide a process for converting a mixture of halocarbons to a mixture of more hydrogenated halocarbons with high selectivity and particularly to provide such a process wherein formation of solids and plugging of reaction vessels is minimized.